Fig. 3.
The stimulatory effect of aldosterone requires Gαq proteins and phospholipase C activity. A: OMCDs were incubated with the inhibitors of small G proteins suramin (200 μM), pertussis toxin (PTX, 200 ng/ml), or GP-2A (20 μM) in the absence and presence of aldosterone (10 nM). Suramin and GP-2A prevented the stimulatory effect of aldosterone, whereas PTX failed to have any effect on the stimulation. B: U-73122 (10 μM), a specific inhibitor of phospholipase C activity, prevented the effect of aldosterone. The values of control and aldosterone-treated OMCDs are shown again for comparison. C: the inactive U-73122 analog U-73343 (10 μM) could not prevent the stimulatory effect of aldosterone. Control and aldosterone values were obtained from a separate set of experiments but yielded qualitatively similar values to the previous experiments listed in Table 2 (n = 5–7 OMCDS from at least three different mice and 50–70 intercalated cells examined per condition). Values are presented as means ± SE. *P < 0.05 and ***P < 0.001 significantly different from control, ###P < 0.001 significantly different from aldosterone alone.